In the US, bone grafts are most commonly used in spinal fusion surgery and, more generally, in the fusion or arthrodesis of any skeletal joint. In addition, bone graft is generally used in trauma surgery for the treatment of fresh fractures and non-unions, which are typically identified as fractures within 6 months that have not healed properly. The bone graft materials typically bridge a gap between bone segments and may also provide a three-dimensional scaffold on which the bone can grow.
Bone graft treatment is also typically used in conjunction with fresh fractures where the bone has been shattered or where the patient is at a very high risk of developing a non-union fracture. Because many fractures are not this severe and can be treated with alternative methods of fixation, bone grafts are not frequently needed during fresh fracture treatments.
Two areas where bone grafts are used is in conjunction with joint reconstruction and joint revision. For example, the bone graft may be used to fill a void between the bone and joint implant in a joint reconstruction surgery. Joint revision is much more likely to need a bone graft because a large void may result from the removal of the original implant. Joint revisions that use bone graft material therefore usually require a relatively large quantity of the bone graft material.
There are different types of bone graft materials that may be used to assist a patient's body in bone regeneration. These bone graft materials are typically classified as either natural or synthetic materials.
Natural bone graft materials are classified in the following groups. Autograft is bone graft material that is obtained from the same individual that will receive the bone graft material. Allograft is bone graft material that is obtained from another human source, which typically is from cadavers. Xeongraft is bone graft material that is obtained from another species.
Bone grafts can also be categorized by their bone-forming properties as osteoconductive, osteoinductive or osteogenic. Osteoconductivity is the ability of a material to provide an appropriate scaffold or matrix upon which new bone tissue can form. Osteoinductivity is the ability of a material to stimulate the patient's own system to form new bone. Osteogenic material generates new bone tissue itself. Osteoblasts, which can be found in bone marrow and mesenchymal cells, are the only cells that can create new bone.
Autograft bone has historically been the standard of care because of its osteoconductive, osteoinductive and osteogenic properties. At the time of surgery, bone is taken from a donor site in the patient, often the iliac crest bone but others are used, and then is re-implanted back into the patient at the surgical site.
Autograft is often not used, because obtaining the graft generally requires a second surgical procedure with associated risks and expenses. The autograft also typically results in significant post-operative issues, most significantly pain. An additional type of autograft, concentrated cells from bodily fluids such as blood or bone marrow, is often used as well.
In addition to autograft, many other types of bone graft are used including processed cadaver bone, i.e., allograft, in the form of demineralized bone matrix and also so called “living cell” or “stem cell” allograft. Additionally, constituents know to be involved in new bone formation, such as bone morphogenic proteins, typically produced by recombinant processing means, as used. Synthetic materials such as tri-calcium phosphate, calcium sulphate, hydroxyapatite and others are used as well.